Proteoglycans will be purified and characterized from human and rabbit lung parenchymal tissue as well as the tracheobronchial tree. The structure of the purified molecules will be determined with respect to glycosaminoglycan content, protein content, and structure and glycopeptides. Changes in structure and composition will be followed with maturation and aging. The difference in the content, the heparan sulfate and dermatan sulfate proteoglycans will also be followed. The nature of proteoglycans synthesized in organ and cell culture will be compared to those synthesized by the native tissue and an attempt to determine the cell types that synthesized the major proteoglycans will be made.